B08_Solicitation_SF_1442_Section_J_Attachment_5_Geophysical_Survey_Report.pdf

GEOPHYSICAL REPORT

SALT RIVER BAY NATIONAL HISTORIC

SITE AND ECOLOGICAL PRESERVE

ST. CROIX, USVI

Submitted to:

Liollio Architecture; Aaron Bowman & Rick Bousquet

Prepared by:

Manuel E. Candelario Cosme, MSCE, PE

Tanayshalí Meléndez, BSCE

Date:

January 7, 2021

Job. No 8145

This report contains 51 pages including this cover.

Table of Content

1.0 INTRODUCTION:

2.0 FIELD WORK:

2.1 Geophysical Survey:

2.2 Concrete coring and testing:

3.0 SUMMARY OF RESULTS:

3.1 Building A:

3.2 Building B:

3.3 Building C:

3.4 Building D:

3.5 Building E:

3.6 Building F:

3.6 Building G:

3.7 Building Tower:

4.0 EXCLUSIONS:

GEOPHYSICAL SURVEY PERFORMED AT

SALT RIVER BAY NATIONAL HISTORIC SITE

ST. CROIX, USVI

1.0 INTRODUCTION:

Jaca & Sierra Engineering, PSC was contracted by Rick Bousquet from Liollio Architecture to perform geophysical surveys and concrete extractions to complement a structural evaluation to be performed by others. The scope of work was defined in the Structural

Geotechnical Scope section from the Geotechnical Supplemental Scope Information document developed and provided by National Park Service (NPS). This report will present the results of the geophysical survey, concrete core extraction, and compression strength test results.

Figure 1 presents a satellite image of the approximate project site location.

Figure 1: Satellite Image of Project Site (17.779864°, -64.761695°) Satellite Imagery obtained from

Google Earth.

Project Site

Page 2 of 19 – Job No. 8145 Salt River Bay National Historic Site, St. Croix, USVI January 14, 2021

P O B o x 3 6 3 1 1 6 , S a n J u a n , P R 0 0 9 3 6 - 3 1 1 6

( 7 8 7 ) 7 6 1 - 2 5 7 0 ( 7 8 7 ) 7 4 8 - 6 9 7 0 w w w . j a c a s i e r r a . c o m

Building identifications were defined in the scope of work provided by NPS as illustrated in Figure 2 below. Refer to Appendix A for an enhanced image.

2.0 FIELD WORK:

2.1 Geophysical Survey:

The field work consisted in performing geophysical surveying of various structural elements as requested in the scope of work provided to us. In all buildings, surveys were performed on walls and ground slabs with the purpose of identifying the spacing and cover

Figure 2: Salt Bay River Historic Site.

Page 3 of 19 – Job No. 8145 of the steel rebars (if any). This data was used to develop the schematics presented in

Appendix A.

The geophysical survey was performed by means of the Ground Penetration Radar

(GPR) with SIR 3000 computer and 1600 MHz antenna and radio detection equipment known as the Pipe Duct Locator (PDL). The GPR method consists of trailing an antenna through the test area while a periodic pulse is transmitted and received. The electromagnetic wave pulses are transmitted at the antennas center frequency of 300 and 1600 Mhz. Pulses propagate through the test medium directly under the antenna. The energy is reflected to the receiver whenever a change in electric impedance is encountered, such as the one produced by a steel rebar, conduit, void, or metal obstruction. The received signal is amplified and filtered in the

GPR computer. The antenna 1600 mhz was used to identify existing steel reinforcement and used to determine its spacing in different walls thought the structure.

A distance wheel odometer records distance along the test path, allowing for the determination of relative location of features from the starting point. A GPR survey is designed by establishing an “X, Y” axis and performing scans along parallel lines drawn at an offset distance. In this case, an offset of approximately 10 ft was used between surveys.

The resulting raw data is obtained in the form of echo amplitude versus time. The material’s dielectric constant is used to define velocity which is then used to convert echo time data to echo depth.

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The conversion may be explained by the following equation:

VEM = c/εr0.5, D = (VEM T)/2 where "VEM" is the materials electromagnetic velocity, "c" is the speed of light, "εr" is the dielectric constant, "D" is depth below ground surface, and "T" is the two-way radar pulse travel time. Scans are typically viewed as waterfall plots of all scans along test path.

Lightness or darkness of the plot indicates amplitude and polarity.

2.2 Concrete coring and testing:

After completion of the geophysical surveys, concrete cores were performed at various locations (including walls, floor slabs and columns) with the purpose of identifying the thickness of the elements and to test the compressive strengths of the extracted samples. A total of sixty-one (61) cores (completed as per ASTM C42) were distributed as follows:

● Twenty-three (23) cores on walls (Buildings A, E, F, G);

● Fourteen (14) cores on walls (Buildings B, C, D);

● Twenty-three (23) cores on floor slabs;

● One (1) core on the closed staircase.

The location of the cores is illustrated in Appendix A. The following subsections present a summary of the findings at each Building.

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3.0 SUMMARY OF RESULTS:

3.1 Building A:

A total of 9 cores were completed on this building: 4 on walls; 3 on floor slabs; 2 on columns. The following table provides a summary of the findings.

Table 1: Results Building A

Core ID Tested Element Type Reinforcement Thickness

(inches) Compression Strength (psi)

Vertical Spacing (inches)

Horizontal Spacing (inches)

8 Column Reinforced Concrete Steel Rebars 10 to 12 1023 10 12 to 32

11 Floor Slab Concrete Wire Mesh 7 to 8 2752 11 to 12 11 to 12 M-1 Wall Masonry None 7 to 8 - - - M-2 Wall Masonry None 7 to 8 - - - M-3 Wall Masonry None 7 to 8 - - - M-4 Wall Masonry None 7 to 8 - - -

ASF-1 Floor Slab Concrete Wire Mesh 7 to 8 4650 11 to 12 11 to 12 ASF-2 Floor Slab Concrete Wire Mesh 7 to 8 3980 11 to 12 11 to 12

AWF-1 Column Reinforced Concrete Steel Rebars 10 to 12 1350 10 12 to 32

3.2 Building B:

A total of 11 cores were completed on this building: 6 on walls; 4 on floor slabs; 1 on columns. The following table provides a summary of the findings.

Page 6 of 19 – Job No. 8145

Table 2: Results Building B

Core

ID

Tested Element Type Reinforcement Thickness

(inches) Compression Strength (psi)

Vertical Spacing (inches)

Horizontal Spacing (inches)

2 Column Reinforced Concrete Steel Rebars 10 to 12 1497 8 to 9 16 to 24

10 Floor Slab Concrete Wire Mesh 7 to 8 2364 6 to 7 6 to 7 M-5 Wall Masonry None 7 to 8 - - - M-6 Wall Masonry None 7 to 8 - - - M-7 Wall Masonry None 7 to 8 - - - M-8 Wall Masonry None 7 to 8 - - -

BWB-1 Wall Masonry None 7 to 8 - - - BWB-2 Wall Masonry None 7 to 8 - - - BSF-1 Floor Slab Concrete Wire Mesh 5 to 6 1580 10 to 12 10 to 12 BSF-2 Floor Slab Concrete Wire Mesh 5 to 6 2420 10 to 12 10 to 12 BSF-3 Floor Slab Concrete Wire Mesh 5 to 6 3780 10 to 12 10 to 12

3.3 Building C:

A total of 12 cores were completed on this building: 4 on walls and 8 on floor slabs.

The following table provides a summary of the findings.

Table 3: Results Building C

Core ID Tested Element Type Reinforcement Thickness

(inches) Compression Strength (psi)

Vertical Spacing (inches)

Horizontal Spacing (inches)

5 Wall Reinforced Concrete Steel Rebars 6 to 7 1826 7.5 to 8 24 to 27

6 Floor Slab Concrete Wire Mesh 4 to 5 3104 6 to 7 6 to 7 M-9 Wall Masonry None 7 to 8 - - - M-11 Floor Slab Concrete Wire Mesh 7 to 8 - 6 to 7 6 to 7

CWB-1 Wall Masonry None 7 to 8 - - - CSL-1 Floor Slab Concrete Rebars 8 to 9 2580 10 to 12 14 to 18 CSL-2 Floor Slab Concrete Rebars 4 to 5 2130 10 to 12 14 to 18 CSL-3 Floor Slab Concrete Rebars 8 to 9 1480 10 to 12 14 to 18 CSB-1 Floor Slab Concrete Rebars 7 3540 6 to 7 6 to 7 CSF-1 Floor Slab Concrete Rebars 8 to 9 2450 7 to 8 17 to 18 CSF-2 Floor Slab Concrete Rebars 8 to 9 3940 7 to 8 17 to 18 CSF-3 Floor Slab Concrete Rebars 7 to 8 1080 11 to 12 11 to 12

Page 7 of 19 – Job No. 8145

3.4 Building D:

A total of 6 cores were completed on this building: 4 on columns and 2 on floor slabs. The following table provides a summary of the findings.

Table 4: Results Building D

Core ID Tested Element Type Reinforcement Thickness

(inches) Compression Strength (psi)

Vertical Spacing (inches)

Horizontal Spacing (inches)

3 Column Reinforced Concrete Steel Rebars 10 to 12 1289 9 to 10 20 to 23

7 Column Reinforced Concrete Steel Rebars 10 to 12 2114 9 20 to 23

DWB-1 Wall Masonry None 6 to 7 1510 - - DWB-2 Wall Masonry None 6 to 7 1790 - - DSF-1 Floor Slab Concrete Wire Mesh 8 to 9 1790 10 to 12 14 to 18 DSF-2 Floor Slab Concrete Wire Mesh 8 to 9 2310 10 to 12 14 to 18

3.5 Building E:

A total of 8 cores were completed on this building: 7 on walls and 1 on floor slabs.

The following table provides a summary of the findings.

Table 5: Results Building E

Core

ID

Tested Element Type Reinforcement Thickness

(inches) Compression Strength (psi)

Vertical Spacing (inches)

Horizontal Spacing (inches)

1 Wall Reinforced Concrete Steel Rebars 6 to 7 2017 6 to 10 12 to 20

M-12 Wall Masonry None 6 to 7 - - - M-13 Wall Masonry None 7 to 8 - - - M-14 Wall Masonry None 6 to 7 - - - M-15 Wall Masonry None 6 to 7 - - - M-16 Wall Masonry None 6 to 7 - - - M-17 Wall Masonry None 6 to 7 - - - ESF-1 Floor Slab Concrete Rebars 5 to 6 3420 6 to 8 17 to 20

Page 8 of 19 – Job No. 8145

3.6 Building F:

A total of 10 cores were completed on this building: 6 on walls and 4 on floor slabs.

The following table provides a summary of the findings.

Table 6: Results

Building F

Core

ID

Tested Element Type Reinforcement Thickness

(inches) Compression Strength (psi)

Vertical Spacing (inches)

Horizontal Spacing (inches)

1 Floor Slab Concrete Wire Mesh 5 to 6 4226 6 to 7 6 to 7 M-18 Wall Masonry None 7 to 8 - - - M-19 Wall Masonry None 7 to 8 - - - M-20 Wall Masonry None 7 to 8 - - - FSF-1 Floor Slab Concrete Wire Mesh 5 to 6 2010 6 to 7 6 to 7 FSF-2 Floor Slab Concrete Wire Mesh 5 to 6 1200 6 to 7 6 to 7 FSF-3 Floor Slab Concrete Wire Mesh 5 to 6 4510 6 to 7 6 to 7

FWB-1 Wall Masonry None 7 to 8 - - - FWB-2 Wall Masonry None 7 to 8 - - - FWB-3 Wall Masonry None 7 to 8 - - -

3.6 Building G:

A total of 4 cores were completed on this building: all cores on walls. The following table provides a summary of the findings.

Table 7: Results Building G

Core

ID

Tested Element Type Reinforcement Thickness

(inches) Compression Strength (psi)

Vertical Spacing (inches)

Horizontal Spacing (inches)

M-21 Wall Masonry None 7 to 8 - - - M-22 Wall Masonry None 7 to 8 - - - M-23 Wall Masonry None 7 to 8 - - - M-24 Wall Masonry None 7 to 8 - - -

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3.7 Building Tower:

Only one core was performed at a wall. The following table provides a summary of the findings.

Table 8: Results Tower

Core

ID

Tested Element Type Reinforcement Thickness

(inches) Compression Strength (psi)

Vertical Spacing (inches)

Horizontal Spacing (inches)

9 Wall Reinforced Concrete Steel Rebars 7 to 8 3613 9 to 11 8 to 12

4.0 EXCLUSIONS:

This report excludes any structural evaluation and engineering recommendation. The scope of work consisted in the Structural Testing and Investigation section from the

Geotechnical Supplemental Scope Information document developed and provided by

National Park Service (NPS) which stated the type of testing to be conducted.

Note that these results are based on geophysical survey, concrete core extraction, and compression strength test results chosen by the client, which are considered as representative of the entire elements from which they were obtained.

Page 10 of 19 – Job No. 8145

We wish to thank you for the opportunity of being of service.

Cordially, JACA & SIERRA ENGINEERING, PSC

Manuel E. Candelario Cosme, MSCE, PE

Tanayshalí Meléndez Santana, BSCE

Enclosures Appendix A: Surveyed Areas and Building Divisions Appendix B: Concrete Cores- Building A Appendix C: Concrete Cores- Building B Appendix D: Concrete Cores- Building C Appendix E: Concrete Cores- Building D Appendix F: Concrete Cores- Building E Appendix G: Concrete Cores- Building F Appendix H: Concrete Cores- Building T

Appendix A

Surveyed Areas and Building Divisions

Appendix A: Surveyed Areas and Building Divisions

Appendix A1: First Level Wall Cores Summary

AWF-1

M-1

M-3 M-2

M-4

M-18

M-19 M-20

M-21

M-5

M-6 M-7

M-8 M-9

M-13

M-12

M-14

M-17

M-15

M-16

Legend:

Wall

Reinforced Concrete

Masonry

Appendix A2: Basement Level Wall Cores Summary

FWB-3

FWB-2

FWB-1

BWB-1 BWB-2

CWB-1

DWB-2

DWB-1

Legend:

Wall

Reinforced Concrete

Masonry

Drill bit *Note: Drill bit were performed to confirm masonry wall.

Appendix A3: First Level Slab Cores Summary

ASF-2

CSF-3 M-11

CSL-1 CSL-2

CSL-3

CSF-1

DSF-1

CSF-1

ESF-1FSF-1

FSF-2

FSF-3

BSF-3 BSF-2 BSF-1

ASF-1

Legend:

Slab

RC Floor Slab

Appendix A4: Basement Level Slab Cores Summary

CSB-1

Legend:

Appendix B

Concrete Cores- Building A

A

Appendix B: Concrete Cores - Building A

Legend:

Wall

Reinforced Concrete

Masonry

Slab

RC Floor Slab

ASF-1

ASF-2

M-2

M-3

AWF-1M-1

M-4

A Vertical Rebar Spacing= 10 inches.

NOTES:

Horizontal Rebar Spacing Varies=12.00 , 22.00 and 32.00 inches.

Concrete cover = 2.30 inches (Applies to horizontal and vertical rebar spacings).

Extracted Core No.8

Sewer Pipe

32”

12”

22”

Appendix B1: Concrete Cores - Building A

A

Rebar Spacing= 11.00 to 12.00 inches.

Concrete cover =4.00 inches (Steel Wire

Mesh reinforcement)

Extracted Core No.11

Appendix B2: Concrete Cores - Building A

Appendix C

Concrete Cores- Building B

B

BSF-3 BSF-2 BSF-1

M-5

M-6 M-7

M-8

Appendix C: Concrete Cores - Building B – 1st Level

Legend:

Wall

Reinforced Concrete

Masonry

BWB-1 BWB-2

Appendix C1: Concrete Cores - Building B – Basement Level

Legend:

Wall

Reinforced Concrete

Masonry

Vertical Rebar Spacing = 9.00 to 10.00 inches.

Concrete Cover =3.00 inches.

Rebar Spacing= 15.00 to

17.00 inches. Concrete Cover= of 2.00 inches.

Rebar Spacing=28.00 inches. Concrete Cover= 2.00 inches.

Horizontal Rebar Spacing= 15.00 to

17.00 inches.

Concrete Cover = 2.00 inches.

Appendix C2: Concrete Cores - Building B

Horizontal Rebar Spacing=

16.00 to 24.00 inches.

Concrete Cover= 2.00 inches.

Vertical Rebar Spacing= 8.00 to 9.00 inches.

Concrete Cover= 2.50 inches.

Extracted Core No.2

Appendix C3: Concrete Cores - Building B

Spacing= 6.00 to 7.00 in.

(Steel Reinforcement)

Extracted Core No.10

Extracted Core No.10 (extracted one core with Wire Mesh Steel Reinforcement)

Appendix C4: Concrete Cores - Building B

Appendix D

Concrete Cores- Building C

C

M-11

CSF-3

CSL-1 CSL-2

CSL-3

CSF-1

M-9

Appendix D: Concrete Cores - Building C – 1st Level

Legend:

Wall

Reinforced Concrete

Masonry

CSB-1

Appendix D1: Concrete Cores - Building C – Basement Level

Legend:

Vertical Rebar Spacing= 7.50 to 8.00 inches.

Concrete Cover = 2.00 inches.

Horizontal Rebar Spacing= 24.00 to

27.00 inches. Concrete Cover= 1.50 inches.

Extracted Core No.5

Appendix D2: Concrete Cores - Building C

Rebar Spacing = 6.00 to

7.00 inches (Wire Mesh

Steel Reinforcement)

Extracted Core No.6

Appendix D3: Concrete Cores - Building C

Appendix E

Concrete Cores- Building D

D

DSF-1

DSF-2

Appendix E: Concrete Cores - Building D – 1st Level

Legend:

Wall

Reinforced Concrete

Masonry

DWB-1

DWB-2

Appendix E1: Concrete Cores - Building D – Basement Level

Legend:

Wall

Reinforced Concrete

Masonry

Horizontal Rebar

Spacing= 20.00 to

23.00 inches.

Concrete Cover=

4.00 to 5.00 inches.

Vertical Rebar Spacing = 8.50 inches.

Concrete Cover= 5.00 to 6.00 inches.

Extracted Core No.7

Appendix E2: Concrete Cores - Building D

20.00 to 23.00 inches.

Concrete Cover= 1.50 inches.

Vertical Rebar Spacing= 9.00 to

10.00 inches.

1.50 in. of cover approx.

Extracted Core No.3

Appendix E3: Concrete Cores - Building D

Vertical Rebar Spacing= 8.00 to 9.00 inches. Concrete Cover= 3.00 inches.

Horizontal Rebar Spacing=

18.00 to 21.00 inches.

Concrete Cover=

4.00 inches.

Appendix E4: Concrete Cores - Building D

Vertical Rebar Spacing= 10.00 to

12.00 inches.

Concrete Cover=

7.00 inches. .

Horizontal Rebar Spacing= 14.00 to 18.00 inches. Concrete Cover=

6.00 inches.

Note:

Slab Thickness = 8 to 9 inches.

Appendix E5: Concrete Cores - Building D

Appendix F

Concrete Cores- Building E

E

M-13

ESF-1

M-14

M-17

M-16

M-15 M-12

Appendix F: Concrete Cores - Building E

Legend:

Wall

Reinforced Concrete

Masonry

Masonry Block Wall

Vertical Rebar Spacing= 6.00 to

10.00 inches. Concrete Cover=

5.00 inches.

Horizontal Rebar Spacing= 12.00 and 20.00 inches. Concrete

Cover= 5.00 inches.

Extracted Core No.1 (extracted one core with reinforcement rebar)

Appendix F1: Concrete Cores - Building E

17.00 to 20.00 inches. Concrete cover= 6.50 inches.

Vertical Rebar Spacing=

6.00 to 8.00 inches.

Concrete cover= 5.60 inches.

Appendix F2: Concrete Cores - Building E

Appendix G

Concrete Cores- Building F

FSF-1

M-20

F

M-19

M-18

FSF-2

FSF-3

Appendix G: Concrete Cores - Building F – 1st Level

Legend:

Wall

Reinforced Concrete

Masonry

FWB-1

F

FWB-2

FWB-3

Appendix G1: Drill Bit- Building F- Basement Level

Legend:

Wall

Drill bit*

*Note: Drill bit were performed to confirm masonry wall.

F

Vertical Rebar Spacing = 6.00 to 7.00 inches. (Wire Mesh

Steel Reinforcement)

Extracted Core No.12

Appendix G2: Concrete Cores - Building F- Basement Level

Appendix H

Concrete Cores- Building T

T

Appendix H: Concrete Cores - Building T

Legend:

Wall

Reinforced Concrete

Masonry

T Vertical Rebar Spacing=

9.00 to 11.00 inches.

Concrete Cover= 2.00 inches.

Horizontal Rebar Spacing= 8.00 to 12.00 inches. Concrete Cover=

1.00 inches.

Appendix H1: Concrete Cores - Building T

4.0 EXCLUSIONS: